1. Field of the Disclosure
The disclosure refers to a leak detection device as well as to a method for checking objects for fluid tightness by means of a leak detection device.
2. Discussion of the Background Art
Known counter-flow leakage search devices, as they are known for instance from EP 1 585 951, use a turbomolecular pump for leak detection. An object to be tested or a test chamber, in which the object under test is arranged, is connected to a backing pump via a test gas line. Further, the test gas line is connected to two or more intermediate inlets of the turbomolecular pump. The backing pump is connected to the outlet of the turbomolecular pump. At the inlet of the turbomolecular pump, a test gas detector is arranged, in particular in a chamber evacuated by the turbomolecular pump. This allows for the use of a test gas detector with a very high sensitivity. Detecting the test gas, which in particular is helium, is effected by the test gas flowing to the inlet within the turbomolecular pump against the main flow direction of the turbomolecular pump, whereby it can be detected by the test gas detector.
In EP 1 585 951, the test gas line is connected to the outlet region of the turbomolecular pump for a rough examination of the object. Because of the connection of the test gas line with the outlet region of the turbomolecular pump, the counter or return-flow path of the test gas is rather long within the turbomolecular pump. Only at a lower pressure in the test gas line can the test gas line be connected with an intermediate region of the turbomolecular pump, so that the counter-flow path is shortened. The test gas can be introduced into this intermediate region of the turbomolecular pump, if the pressure in the test gas line corresponds to the pressure in the intermediate region of the turbomolecular pump, leaving aside insignificant variations. Thus, a connection of the test gas line with a further intermediate inlet, whereby the counter-flow path is shortened further, is possible only at a later moment, when the test pressure is reduced further. Since the counter or return-flow paths are long, especially in the beginning of an examination of an object, the testing times and the response times are relatively long.
It is an object of the present disclosure to provide a leak detection device and a corresponding method for testing objects for tightness, by which testing times can be shortened.